KR20110039216A - Sound absorption material and method of manufacturing sound absorption material - Google Patents

Abstract

The present invention relates to a method for producing a sound absorbing material. The method comprises the steps of forming a low viscosity fibrous web that acts as a porous bulk absorber (the fibrous web comprises a plurality of bicomponent fibers, each bicomponent fiber having a shell material around the core material and the core material). The shell material has a lower melting point than the core material); Applying a surface layer to the fibrous web, where the surface layer is suitable for adhering to the sheath material; Heating the fibrous web to a temperature sufficient to soften the sheath material of at least a portion of the bicomponent fiber; Compressing the surface layer and the fibrous web together under low pressure to contact at least a portion of the surface layer with the softened sheath material of at least a portion of the bicomponent fiber to form an adhesive bond between the surface layer and the fibrous web.

Description

Sound absorption material and method of manufacturing sound absorption material

The present invention relates generally to methods of making sound absorbing materials and materials produced by such methods.

Sound-absorbing materials are used in a variety of applications, including automobiles, machinery, and buildings. Such materials serve to reduce noise transmission and / or reflection in certain applications and may be made of fiber materials.

The present invention seeks to address or alleviate or at least provide a useful alternative to one or more disadvantages or disadvantages associated with existing sound absorbing materials and / or methods of making such materials.

Certain embodiments relate to a method of making a sound absorbing material. The method includes forming a low viscosity fibrous web that acts as a porous bulk absorber, the fibrous web comprising a plurality of bicomponent fibers, each bicomponent fiber being around the core material and the core material. The shell material has a lower melting point than the core material. The method further includes applying a surface layer to the fibrous web, wherein the surface layer is suitable for bonding with the skin material. The method further includes heating the fibrous web to a temperature sufficient to soften the sheath material of at least a portion of the bicomponent fiber. The method further includes compressing the surface layer and the fibrous web together under low pressure such that at least a portion of the surface layer contacts the softened sheath material of at least a portion of the bicomponent fiber to form an adhesive bond between the surface layer and the fibrous web.

The surface layer may comprise a film layer having a thickness of 5 to 100 microns. The thickness can optionally be about 10 to 25 microns. In addition, the thickness of the film layer may be about 15 microns. The thinner the film, the better it is, as long as the film has sufficient structural integrity to withstand damage or breakage during normal processing.

The fibrous web may have a thickness of about 4 to 50 millimeters before being compressed with the film layer. In addition, the thickness of the fibrous web may be about 4 to 25 millimeters. Although various thicknesses may be used for the fibrous web, the practical maximum thickness is about 50 millimeters and the practical minimum thickness is about 4 millimeters.

The low pressure when the surface layer and the fibrous web are compressed together may be that the fibrous web is compressed to about 5% to 80% of its thickness. This pressure can be applied evenly across the fibrous web to increase the bulk density substantially throughout the fibrous web.

The temperature at which the fibrous web is heated to soften the sheath material of the bicomponent fiber depends on the physical properties of the sheath material. For polyethylene sheaths, the temperature can be from about 140 ° C to about 160 ° C. In addition, the temperature may be about 150 ° C. For polypropylene sheaths, the temperature may be higher, for example about 180 ° C.

According to some embodiments, the method may further comprise applying a second surface layer to the second surface of the fibrous web, the second surface layer being suitable for bonding with the sheath material. Compression involves compressing the second surface layer and the fibrous web together under low pressure such that at least a portion of the second surface layer contacts the softened sheath material of at least a portion of the bicomponent fiber to form an adhesive bond between the second surface layer and the fibrous web. It may include. The second surface layer may comprise the same material as the first surface layer. Also, the materials of the first and second surface layers can be different, in which case the thickness of the surface layers can be different.

According to other embodiments, the fibrous web can be a first fibrous web and the method compresses the second low density fibrous web together under low pressure to compress the second surface layer together to adhere the first side of the second fibrous web to the second surface layer. It may further comprise a step. The second fibrous web may comprise portions of a plurality of bicomponent fibers, each having a core material and a shell material in the manner of the bicomponent fibers described above for the first fibrous web.

The method may further comprise applying an adhesive material to the first side of the second fibrous web before compressing the second fibrous web with the second surface layer. The adhesive material is suitable for bonding both the second surface layer and the second fibrous web. The adhesive material may be provided in the form of a hot melt adhesive powder, web, net, spray or film. The method may further comprise activating the hot melt adhesive material to form a permanent bond between the two layers prior to contacting the second fibrous web with the second film. The hot melt adhesive may comprise one of polyethylene, polypropylene, EVA or polyamide or other suitable polymer for bonding with an appropriate melting temperature. The adhesive material may comprise a water or solvent based adhesive system or may comprise a pressure sensitive adhesive applied according to known lamination processes.

The method may further comprise applying a third surface layer to the second side of the second fibrous web. The third surface layer may be suitable for adhering to the sheath of the bicomponent fibers of the second fibrous web. The method may further comprise heating the second fibrous web to a temperature sufficient to soften the sheath material of at least a portion of the bicomponent fibers. The method employs the third surface layer and the second fibrous web under low pressure such that at least a portion of the third surface layer contacts the softened sheath material of at least a portion of the bicomponent fiber to form an adhesive bond between the third surface layer and the second fibrous web. Compressing together may further comprise.

The bicomponent fibers can be mixed into the structure of the fibrous web. The bicomponent fibers are cut from the extracted bicomponent fibers and formed into short lengths. The core of the bicomponent fiber may have a linear mass density of about 2 to about 6 denier per fiber filament. The bicomponent fiber may have a sheath to core ratio (in cross-sectional area) of about 25% to 35%, for example about 30%. The bicomponent fiber may have a staple length of between about 3-4 millimeters and about 70 millimeters for worn fiber webs. For example, as described herein, the length of a bicomponent fiber is about 32 to about 64 millimeters, has an average or common length of about 51 millimeters staple length, and is representative of the length used in fiber carding processes. to be. Short bicomponent fibers can be used in some other nonwoven processes, such as the formation of air laid fibrous webs.

The surface layer may only adhere to the outer material of the bicomponent fiber in the fibrous web. In some embodiments, the low density fibrous web is a porous volume absorbent having an air flow resistivity of at least about 1,000 and less than 60,000 mks Rayls / m. The air flow resistivity can optionally be about 2,500 to about 40,000 mks Rayls / m or about 3,000 to about 20,000 mks Rayls / m. The air flow resistivity may optionally be about 5,600 mks Rayls / m.

The low density fibrous web may have a bulk density of less than about 120 kg / m ³ . In addition, the density may be less than about 60 kg / m ³ . In addition, the density may be less than about 30 kg / m ³ . In addition, the density may be less than about 15 kg / m ³ . The density may be as low as about 10 kg / m ³ , but will generally be higher due to practical considerations such as mechanical integrity. The density of the embodiments disclosed herein varies from about 14 to about 56 kg / m ³ .

In some embodiments, the surface layer may comprise a linear low density coextruded polyethylene film about 15 microns thick.

The fibrous web can be produced by a nonwoven fabric manufacturing process comprising mixing the adhesive bicomponent fibers with conventional staple fibers and forming the web. The fibrous web may be formed by a cross wrap, vertical wrap, air-laid or other typical nonwoven web-forming process. After web formation, the fibrous web may be joined via air bonding or may be mechanically strengthened by, for example, a needling process. After mechanical reinforcement, the fibrous web can be thermally bonded. Preferred embodiments are not limited in terms of fiber orientation.

The adhesive envelope material of the bicomponent fiber may be formed of low surface energy polymers suitable for adhering to the selected surface layer or layers. The polymers for the adhesive sheath of the bicomponent fiber may be selected from the group consisting of polyethylene, polypropylene, polyamide and co-polyester. The core of the bicomponent fiber can be, for example, polyester.

It is included in the content of this invention.

Embodiments are described in more detail below by way of example only with reference to the accompanying drawings and examples:
1 is a flow chart of one embodiment of a method of making a sound absorbing material;
2 is a graph of sound absorption coefficient against frequency of Examples 1 and 2;
3 is a graph of sound absorption coefficients for frequencies of Examples 3, 4 and 5;
4 is a graph of sound absorption coefficients for frequencies of Examples 6, 7 and 8;
5 is a graph of sound absorption coefficient against frequency of Examples 9 and 10;
6 is a schematic diagram of a sound absorbing material shown in cross section;
7 is a schematic diagram of a process for producing a fibrous web for sound absorbing material;
8 is a schematic diagram of a system for producing a sound absorbing material;
9 is a schematic diagram of a system for producing a multilayer sound absorbing material;
10 is a sectional view of a multilayer sound absorbing material;
11 is a flowchart of a method of producing a multilayer sound absorbing material;
12 is a graph of sound absorption coefficients for frequencies of Examples 11, 12, and 13;

In dry lamination, the thermoplastic resin melts to create adhesion between the surface material and the substrate. In some cases, the surface may comprise a low melting point material that will itself act as a "self-adhesive" surface by applying heat. The adhesive can also be applied in the form of a dry thermoplastic hot melt in the form of a powder, web, net, spray or film. The heat of melting the adhesive resin is applied by direct contact such as hot calendar or indirect contact such as infrared radiation or hot air. The adhesive should be carefully chosen to ensure good adhesion to both the surface and the substrate. For good adhesion, the surface energy of the adhesive should be lower than the surface energy of the substrate.

In wet lamination, water and solvent based adhesives are used to provide adhesion between the surface material and the substrate. Again, the adhesive should be carefully chosen to ensure good adhesion to both the surface and the substrate.

Apart from surface energy, the variables that define effective adhesion by dry lamination of surface-to-fiber webs are the temperature, pressure, and duration of heat applied. If the contact time with the hot roller is short, the adhesion requires the use of relatively high temperature and higher pressure. This impairs the thickness of the fibrous web if the fibrous web does not have sufficient density to withstand the compressive action of the hot roller stack.

Adding a thin film surface to the porous volume absorber can provide much greater sound absorption than the porous volume absorber alone. The thin impermeable film acts as a membrane sound absorber, exhibiting sound absorption peaks corresponding to the depth of the membrane back space corresponding to the resonant frequency of the film and the thickness of the porous volume absorbent. In addition, porous volume absorbers bind to the membrane and provide mechanical and acoustic impedance to the overall system, providing a broad spectrum of sound absorption around the resonance frequency of the membrane.

In order to obtain effective sound absorption over a broad spectrum, the porous volume absorber should have a low modulus and consequently do not provide stiffness to the membrane. In other words, the porous volume absorber, which is the fibrous web serving as the laminate substrate in this case, should have a moderately soft or low compliance. In addition, the film film must be soft and bendable. For example, lightweight plastic films are suitable as film films. In an ideal situation, the membrane would simply be placed on the substrate without any adhesion, but this should be done to allow the membrane to float as freely as possible to the porous volume absorbent while still adhering to the porous volume absorbent. The fibrous web acting as a porous volume absorbent is particularly soft, and the film surface layer has a high flexibility and the film surface layer which is bonded and acts as a membrane has a high degree of freedom.

Fibrous porous volume sound absorbing materials having a thin surface, which is an impermeable single or double surface, can be used to obtain very light weight, high sound absorbing composites that provide the same sound absorption as much thicker and heavier, uncovered materials. Such laminates can be made using a cross-array thermally bonded porous bulk fiber absorbent. However, a fibrous web with fibers arranged to some extent in the vertical direction (i.e., perpendicular to the machine, cross, direction of the web) exhibits excellent mechanical integrity and resistance to delamination due to the orientation of the fibers. Such structures can be found, for example, in vertically-array thermally bonded porous volumetric fiber absorbents made by strutto or V-Lap processes and to a lesser extent in some airlaid nonwoven fibrous webs.

Sound absorbing materials, which are thin film surfaces, can use less raw material and can be produced with less energy compared to heavier, less effective porous volume absorbers and can provide more sound absorption and significantly reduced environmental effects. Such laminates can be made using a hot melt adhesive film applied through a flat plate laminator under controlled temperature, pressure and contact time. Expensive hot melt films can be replaced with thin plastic films such as those used in diaper manufacture, adhered to the web by hot melt adhesive powder or similarly dispersed dispersions of adhesives applied to the fibrous web.

Since the powder dispersing product is applied only to one side of the web, the hot melt film can be applied to the lower side of the web and the powder dispersing product and thin film plastic film can be applied to the upper side of the web, so that the laminate is a double surface, ie To produce a fibrous web having both first and second surface layers. This laminate has the advantage of providing a product which, when used in an automobile, does not require separate left and right components.

The disclosed embodiments will be sound absorbed with a self-laminated fibrous web that will adhere to a suitable surface layer without the need for any adhesive layers and will eliminate the need to use any other adhesive such as adhesive powder, web, film or net or any other type of adhesive. Relates to the production of materials. The adhesion provided is strong enough, but very flexible, allowing the membrane to move relatively freely and optimize the resulting sound absorption.

Some disclosed embodiments include producing a sound absorbing material that is a single-sided film surface without the need to use a hot melt film or any other additives such as adhesive powder, webs, films or nets. Some disclosed embodiments include producing a sound absorbing material that is a double-sided film surface in a single lamination process without the need to use a hot melt film or any other additives such as adhesive powder, webs, films or nets. Further embodiments include two porous volume absorbent layers having one film surface layer between two porous volume absorbent layers and film surface layers on each of the outer surfaces of the dual layer porous volume absorbent material.

Referring to FIG. 1, a flow chart of a method 100 for making a sound absorbing material is described in more detail.

The sound absorbing material of the disclosed embodiments can be produced according to the method 100, which mechanically strongly forms a low density (porous) fibrous web and a plurality of bicomponent fibers mixed with the low density (porous) fibrous web. Or thermally joining 110. Step 110 may include a web forming process 700 as described below with respect to FIG. 7. Each bicomponent fiber has a core material and an adhesive shell having a lower melting point than the core material. Mixing the bicomponent fibers in the fibrous web can be performed by standard mixing or blending techniques that mix the opened staple fibers with the plurality of opened bicomponent fibers.

The temperature difference between the melting points of the other core and the shell material depends on the particular material chosen. However, the melting point of the shell material should be sufficiently lower than the melting point of the core material so that the shell material softens at a temperature near its melting point temperature while the core material maintains its structural integrity. For example, for polyethylene sheath materials, the melting point is around 140 to 160 ° C. In addition, temperatures outside this range can still soften the polyethylene sheath material while maintaining the structural integrity of the core material. In another example, the polypropylene shell material may have a melting temperature on the order of 180 ° C. Thus, the temperature at which the skin material softens depends on the melting point of the particular skin polymer selected to form the skin material of the bicomponent fiber.

The fibrous web is incorporated into a nonwoven process that includes cross-wrapping, vertical wrapping, needle-punching, air laying, or other suitable methods to produce a mixed web of nonwoven material, combined with appropriate mechanical reinforcement or thermal bonding to allow the web to be processed. It can be formed by. The low density fibrous web produced by this process acts as a porous volume absorber and has an air flow resistance of at least about 1,000 and less than about 60,000 mks Rayls / m. The air flow resistance can optionally be about 2,500 to about 40,000 mks Rayls / m or about 3,000 to about 20,000 mks Rayls / m. The air flow resistance can optionally be about 5,600 mks Rayls / m. The density of the fibrous web can be from about 10 kg / m ³ to about 120 kg / m ³ .

In step 120, the film layer is applied to the low density fibrous web as a surface layer and heat is applied in step 130 to soften the sheath of the bicomponent fiber. Steps 120 and 130 may be performed using dry lamination system 800 as shown in FIG. For example, for polyethylene sheath materials, the temperature may be about 140 ° C. to about 160 ° C., possibly about 150 ° C.

Heat may be applied during (or immediately before) or after application of the surface layer. The amount of heating is controlled and the surface layer is selected such that under some circumstances only the skin softens. Under other circumstances where the surface layer comprises a film layer, the film may soften to some extent but does not melt. The temperature of the heating is chosen such that the structural integrity of the fibrous web and film laminate is substantially maintained during the heating process. The core material has a sufficiently higher melting point than the shell material so that the core material substantially retains its structural integrity during lamination despite the softening shell.

The film layer is selected to be suitable for adhering to the material of the skin so that an adhesive bond can be formed between the film and the skin of the bicomponent fiber. In other words, the skin and the film can have relative surface energy to form a strong adhesive bond. Suitable combinations of bicomponent fibers and films generally include polyethylene terephthalate (PET) as the core polymer and other low melting point polymers as the adhesive sheath, for example:

PET core bicomponent fibers having a polyethylene film and having a polyethylene sheath;

PET core bicomponent fibers having a polypropylene film and having a polypropylene sheath;

PET core bicomponent fibers having a polyamide film and having a polyamide sheath;

PET core bicomponent fibers having a polyester film and having a co-polyester sheath.

These examples illustrate the general form of commercially available bicomponent fibers. However, it is to be understood that other combinations of core and shell material are possible and the examples are non-limiting.

In some embodiments, a combination of other types of bicomponent fibers may be used. For example, instead of a fibrous web with 30% PE / PET bicomponent fibers, 10% CoPET / PET and 20% PE / PET bicomponent fibers may be used. The proportion of bicomponent fibers will generally be chosen to minimize the cost associated with more expensive bicomponent fibers, with the minimum amount of bicomponent fibers required to achieve proper adhesion and mechanical integrity.

The film layer and the fibrous web are joined together under low pressure in step 140 using, for example, a flat plate laminator as shown in FIG. 8, such that at least a portion of the film layer is combined with the softened sheath of at least a portion of the bicomponent fiber. In contact to form an adhesive bond without significant compressive or plastic deformation of the fibrous web. The pressure applied to the fibrous web assists the adhesion of the film to the fibrous web and does not significantly change the thickness of the fibrous web. According to the embodiments disclosed herein, the compression of the fibrous web and the film layer did not form a rigid sheath within the fibrous web. Formation of a hard shell will increase the hardness and reduce the sound absorption properties.

In step 150, the bonded fibrous web and the surface layer are cooled to secure the adhesive bond therebetween.

Although the above description of the method 100 refers to a single surface layer laminated to the fibrous web, the fibrous web, which is a double surface, wherein the surface layers can be applied to both sides of the fibrous web in step 120, is described below with respect to FIG. 8. As shown and disclosed, it is heated in step 130 and compressed under relatively low pressure in step 140. Porous volume absorbers that are dual film surfaces have been found to be more effective at sound absorption than volume absorbers that are single film surfaces.

Referring to FIG. 6, a cross-sectional schematic of a sound absorbing material 200 in accordance with some embodiments is shown. The sound absorbing material 200 includes a surface layer 210 and a fibrous web 220 in which various bicomponent fibers 230 are mixed. The surface layer 210 is formed between the surface layer 210 and the sheath 211 of a portion of the bicomponent fiber 230 located within the fibrous web 220 and adjacent to the surface of the fibrous web 220 to which the surface layer 210 is applied. Bonded to the fibrous web 220 by adhesive bonding.

Each of the bicomponent fibers 230 has an outer shell 211 formed around the core material 212. The sheath 211 has a melting point significantly lower than the melting point of the core material 212 so that it does not substantially affect the structural integrity of the core material 212 and melts the sheath material 211 to adhere to the surface layer 210. Or a temperature to soften may be selected.

The fibrous web 220, surface layer 210, and bicomponent fiber 230 of FIG. 6 have the properties disclosed herein and may be used to form a sound absorbing material as described herein and / or in accordance with embodiments.

Although the sound absorbing material 200 is shown in FIG. 6 as having only a single surface layer 210 applied to one side of the fibrous web 220, another surface layer identical to the surface layer 210 or another thin surface layer as disclosed herein In a similar manner it can be applied to the other side of the fibrous web 220 that is bonded to the sheath material 211 of the bicomponent fiber 230. One or both of the surface layers 210 may have material properties suitable for enabling ultrasonic welding of the sound absorbing material 200 to the surface, such as plastic casting for the door trim of an automobile. For such embodiments, the surface layer must be mixed with the material of the plastic casting substrate, which material may comprise talc-filled polypropylene in some embodiments.

In some embodiments, the sound absorbing material 200 can be made to have a density of about 350 gsm and can be about 25 mm thick and has a film surface layer that is a double surface suitable for ultrasonic welding to automotive door trim. Supplying sound absorbing material 200 in this manner eliminates the need for anti-rattle pads to be used in automobiles, thereby reducing vehicle manufacturing costs and reducing the number of parts that need to be installed in a vehicle. . It has been found that low density is desirable for obtaining effective sound absorption. This means that thick materials can be obtained with a relatively small amount of fibers without sacrificing sound absorption to achieve anti-shake properties.

Examples of sound absorbing materials disclosed herein are characterized in that they are self-laminating such that no adhesive needs to be used to adhere the surface layer to the fiber web (except as described below with respect to sound absorbing materials having a double layer fiber web). . In addition, since the fibrous web used for the sound absorbing material 200 or 1000 (FIG. 10) is low density, it is possible to manually treat large rolls of such materials without special lifting devices.

The fibrous web 220 may be a spent, vertically wrapped and thermally bonded web. Fibrous web 755 (FIG. 7) is an example of fibrous web 220. Other fibrous webs can include spent cross wrapped and needle punched webs, air-laid webs, melt-blown webs, and combinations thereof. Other web bonding forms may include resin bonding and mechanical bonding such as needle punching or hydraulic weaving.

The surface layer 210 may comprise a thin flexible cast coextrusion molded film produced by the Stellar Film Group of Melbourne, Australia. The film may comprise a triple layer of linear low density polyethylene (LLDPE) with an adhesive tie-layer. The film may have a small amount of metallocene LLDPE therein to improve mechanical properties such as softness and tear strength and elongation and to reduce noise. Other films such as polypropylene and polyester films may be used in other embodiments. However, metallocene polyolefins provide improved mechanical properties such as rigidity and can be used with thinner thicknesses.

Steps 130 and 140 described above for method 100 may, for example, insert a fibrous web and a single or double thin surface layer into flat laminator 850 (FIG. 8) for dry lamination between heated Teflon belts. It can be done simultaneously by feeding. These laminators apply a slight pressure over a period of time so that the integrity of the fibrous web is not affected and the thickness of the fibrous web is not excessively reduced during the lamination process. However, not all flat plate laminators are suitable. The upper belt needs to prevent sagging, which will undesirably reduce the thickness of the sound absorbing material. Since the fibrous web is usually very soft and does not support the belt weight, it is important that the upper belt of the laminator does not sag, especially since the web is heated and the adhesive fibers are softened.

Self-laid fibrous webs (due to the film compatible bicomponent fibers mixed into the webs) eliminate the other general features of dry lamination systems such as hot melt adhesives, powders, films, nets and webs. In fact, sound absorbing materials using a fibrous web with bicomponent fibers mixed therein can be seen to include an adhesive web in the fiber blend.

The flat plate laminator 850 or 950 (FIG. 9) is made to apply a certain temperature and pressure to the fibrous web or webs and the film layer or layers for a predetermined time (controlled by adjusting the speed of the material passing through the laminator).

Referring to FIG. 7, a process 700 of forming the fibrous web 755 is disclosed in greater detail. The fibrous web 755 includes a blend of bicomponent fibers 707 and standard polyester fibers 705 that are opened and mixed in the bale opener and mixing system 720. The mixed fibers are then consumed using carding system 730 before performing web formation 740. The result of the web formation 740 may be a vertically nested or unbonded web 745, which passes through the thermal bonding system 750 to heat between the thermoplastic fibers of the vertically nested web 745. Provide a bond. The thermally bonded fibrous web 755 may be used as the fibrous web 220 as part of the sound absorbing material 200. In addition, the fibrous web 755 can be used in the formation of sound absorbing materials as shown and disclosed with respect to FIGS.

Referring to FIG. 8, a system 800 for sound absorbing material is described in more detail. System 800 may receive the bonded fibrous web 755 directly from process 700 or from a roll of such fibrous web material. The system 800 includes a film unwinder (not shown) disposed to unwind the film 815 from the roll 812 of such film to form a surface layer on one side of the fibrous web 755. The fibrous web 755 and the film 815 may be conveyed to the flat plate laminator 850 by a conveyor (not shown).

If the system 800 is used to produce a sound absorbing material 940 that is a dual film surface, the surface of the fibrous web 755 opposite the side on which the additional film 840 is released from the roll 845 and the film 815 is applied. Is applied to. Film 840 may be applied to fibrous web 755 concurrently with film 815 and film surface layers 815 and 840 are fed together into flat laminator 850.

The flat plate laminator 850 may have separate upper and lower belts 852, each of which carries a series of rollers to carry the fibrous web 755 and film surface layers 815, 840 through the laminator 850. Pass through. Rollers 856 are disposed at the exit of laminator 850 to compact the materials together as they enter laminator 850. Laminator 850 has a heating zone 862 and a cooling zone 864 for continuously heating and cooling the material layers 755, 815, and 840 as the material layers pass through. The nip roller 868 cools the bicomponent fibers of the fibrous web 755 and the individual film layers 815, 840 to bond the bicomponent fibers of the fibrous web 755 with the individual film layers 815, 840. Positioned on top and bottom belts 852 between heating and cooling zones 862, 864 to slightly compress the heated material layers 755, 815, and 840 together before fixing. The heating zone 862 of the laminator 850 is made to heat the material between about 140 ° C and about 160 ° C.

9-11, a system 900 for the sound absorbing material 1000 according to the method 1100 is described in more detail. The system 900 is a double surface sound absorbing material that can be produced by the system 800 according to the method 100 in step 1110, instead of the film layer 840 applied to one side of the fibrous web 755A. 940 is similar to system 800 except that 940 is applied as a second layer on top of the first fibrous web layer 755A. In addition, the flat plate laminator 950 will generally not be suitable for providing sufficient heat to achieve adhesion of the bicomponent fibers in the fibrous web layer 755A with the film layer 815 of the fibrous web layer 755B. An active adhesive, such as an adhesive powder, is applied to the exposed surface of the fibrous web layer 755A before applying the double-surface sound absorbing material and subsequently passing the bilayer fibrous web material through the flat plate laminator 950.

System 900 is unwinded (not shown) to apply film 915 (step 1130) as an outer surface layer on one side of the fibrous web 755A formed by process 700 at step 1120. ) And a film roll 912 disposed. The fibrous web 755A and the film layer 915 disperse or apply an adhesive material 922 such as adhesive powder onto the side of the fibrous web 755A opposite the side on which the film 915 is applied (step 1140). It passes through an adhesive applicator 920 such as a powder dispersing apparatus. The adhesive material 922 is activated at step 1150 as it passes through an activation device 930, such as an infrared heater that delivers infrared radiation 932 activating the adhesive material 922. Instead of an adhesive powder, a suitable adhesive film may be applied to the fibrous web 755A using an adhesive applicator for subsequent activation and adhesion.

The roller 945 is used to apply the fibrous web layer 755B on the exposed side of the first fibrous web layer 755A with the activated adhesive thereon. The adhesive material 922 is selected to be suitable for bonding the film layer 815 and the fibrous web 755A. The adhesive material may include, for example, LDPE or polyamide powder.

In some embodiments, instead of applying an adhesive to the top surface of the fibrous web 755A, heat may be applied to the top surface to soften the sheath material of the bicomponent fiber 230, which is a film surface layer 815 ) May form a weak adhesive bond when slightly compressed with the fibrous web 755A. Thus, these embodiments may not include additional adhesive other than the softened bicomponent fibers in the fibrous web 755A and may replace the described heating steps for steps 1140 and 1150.

The flat plate laminator 950 can have separate upper and lower belts 952, each of which is carried in series to carry the fibrous webs 755A, 755B and the film surface layers 815, 840, and 915 through the laminator 950. Passes through the rollers. The roller 956 is disposed at the exit of the laminator 850 to squeeze (at step 1160) the materials 755A, 755B, 815, 840 and 915 together as they enter the laminator 950. Laminator 950 has a heating zone 962 and a cooling zone 964 for continuously heating and cooling the material layers 755A, 755B, 815, 840 and 915 as the material layers pass through. The nip roller 968 may be cooled before the bicomponent fibers of the fibrous web 755A and the film layer 915 are cooled to secure the adhesion of the bicomponent fibers and the film layer 915 of the fibrous web 755A in step 1180. The heated material layers 755A, 755B, 815, 840, and 915 are positioned on the upper and lower belts 952 between the heating and cooling zones 962, 964 to slightly compress together at step 1170. The compaction of step 1160 and the weak compaction of step 1170 serve to assist the adhesion of the film layer 815 and the fibrous web 755A by the adhesive material 922. The heating zone 962 of the laminator 950 is made to heat the material between about 140 ° C and about 160 ° C.

A conveyor (not shown) is a preformed sound absorption comprising a second layer of fibrous web 755B with film layers 815 and 840 for heating and slight compression (steps 1160 and 1170). Along with the material 940, it can be used to convey the fibrous web layer 755A and the film layer 915 into the flat plate laminator 950. The flat plate laminator 950 is bonded between the fibrous web 755A and the film layer 815 through the adhesive material 922 and through the adhesion of the film layer 915 with the outer material of the bicomponent fibers mixed into the fibrous web 755A. Relatively low pressure is applied to these materials to achieve adhesion between the fibrous web 755A and the film 915.

The result of the flat panel laminator 950 is shown larger in FIG. 10 with the double layer sound absorbing material 1000. 10 is provided for purposes of illustration and not as an exact accumulation and not as a physical and dimensionally accurate representation of the disclosed embodiments. Some embodiments use vertical wrapping as part of the web forming process, wherein the vertically oriented wavy shapes in the fibrous webs 755A and 755B shown in FIG. 10 are possible webs rather than describing specific fiber shapes, structures or dimensions. As a kind of form it is only intended to represent this vertical wrapping.

Sound absorbing material 1000 has two fibrous web layers 755A and 755B, with a thin surface layer 815 and a thin surface layer 840 and 915 on the outer surface of the final composite sound absorbing material 1000. Depending on the bonding process, the adhesive layer may be formed of adhesive powder 922 or other adhesive material. Sound absorbing material 1000 may have a thickness X of, for example, about 10 mm to about 80 mm. The fibrous web layers 755A and 755B may have approximately the same thickness or may have different thicknesses. In addition, the thin surface layers 815, 840, and 915 may comprise essentially the same material or may be made of other materials if the materials are suitable for bonding with the outer material of the bicomponent fiber mixed into the fibrous web layers 755A and 755B. Can be formed.

The material characteristics of the fibrous webs 755A and 755B, the thin surface layers 815, 840, and 915 are as described above. While FIG. 10 illustrates vertically wrapped fiber web layers 755A and 755, other suitable fiber web structures may be used.

1 and 7 to 11 the embodiments disclosed herein are provided by way of example only. Other systems, methods, and materials, as appropriate, may replace the disclosed embodiments when similar features and functions are obtained as disclosed herein.

Examples

Several samples of fibrous webs were made, each of which is a thermally bonded nonwoven web that is approximately 3-5 mm thicker vertically wrapped with a nominal web weight of 200 gsm to 400 gsm than the finished product required. Part of the fibrous web (blend 1) has staple polyester fibers mixed with bicomponent adhesive fibers comprising a co-polyester sheath and a polyester core. The remaining fibrous web (blend 2) has polyester fibers mixed with adhesive fibers made of polyethylene sheath with a polyester core instead of polyester bicomponent fibers. Details of each blend are shown in Table 1.

fiber Blend One 2 2 denier 2 components (CoPET / PET) 30% Two Denier Two Component Polyolefin / Polyester Fiber 30% 3 denier recycled PET RSF 40% 40% 12 Denier SHCSF (Linear Hollow Bonded Staple Fiber) PET 30% 30% Nominal web density, g / m ² 200 350 Laminating temperature, C 150 150 Laminator belt speed, m / minute 5 5

The plastic film was laminated to the web using a Schatti flat laminator. Similar laminators are provided by Meyer, Reliant, and Glenlowe. In each case, the laminator belt was heated and the belt height was set to the required finished thickness. Samples were passed through the laminator at a speed of about 5 m / minute.

Comparative examples were produced using conventional adhesive-type films activated by the heat of a dry lamination process. A 25 micron polyurethane thermoplastic film made by Ding Jing of Taion was laminated to a web produced from Blend 1 called Example 1 during inspection.

A 20 micron uncoiled coextruded hot melt film, type Xiro V4712, manufactured by Collando, Switzerland, was laminated to a web produced from Blend 1, called Examples 4 and 7, during inspection. An additional layer of Xiro V4712 was laminated to the other side to form a double surface product called Example 9 during inspection.

A 15 micron linear low density polyethylene (LLDPE) cast coextruded three-layer film was provided as the surface layer to be laminated to the webs produced from Blends 1 and 2. Although thermoplastic, the film will not adhere to Blend 1 during the lamination process without the use of 500 micron particle size low density polyethylene (LDPE) adhesive powders called Examples 3 and 6 during the inspection.

The same LLDPE film was laminated to Blend 2 during the lamination process and successfully attached without the need for an adhesive powder called Examples 2, 5 and 8 during the inspection. The PE sheath on the PE / PET bicomponent binder has a lower melting point than the LLDPE film and suitable melt-flow and adhesion properties that make it an excellent adhesive for the LLDPE film, providing an adhesive that is included in the web itself, and a thermoplastic adhesive film. Or eliminating the need for additional adhesives such as adhesive powders. An additional LLDPE film layer was laminated to the other side of the laminate to form a double surface product called Example 10 during inspection.

The samples were then examined for sound absorption in impedance tubes using two microphone techniques according to ASTM 1050E.

The sound absorption of samples produced from Blend 2 laminated to LLDPE film showed significantly higher sound absorption than all of the other samples.

From FIG. 2, the increased sound absorption can be seen in the self-laminating web (Example 2), especially when compared to the thermoplastic polyurethane hot melt film (Example 1) at frequencies above 400 Hz.

From FIG. 3, the increased sound absorption is achieved by using a self-laminated LLDPE film (Example 5), especially when compared to powder-laminated (Example 3) co-extruded hot melt films (Example 4) at frequencies above 400 Hz. It can be seen in the sound absorbing material formed.

From FIG. 4, the increased sound absorption can be seen in the self-laminated web (Example 8) when compared to powder laminated (Example 6) and coextruded hot melt film (Example 7). For these embodiments, the sound absorption is greater than the previous embodiments because of the higher web density than these embodiments. In particular, Example 6 has a web density of 400 gsm while Example 8 has a web density of only 350 gsm. Both use the same film laminated into powder or self-laminated webs. Despite the higher web mass of Example 6, the sound absorption is still much lower than that of Example 8, indicating that the improvement of sound absorption through the use of a self-laminated web is significantly greater than that obtained by an increase in web weight.

From FIG. 5, lamination of films on both sides of the web further improves sound absorption in the case of film-laminated webs, more particularly self-laminated webs. Example 10 shows a large increase in sound absorption compared to Example 9. This will also generally result in higher sound absorption, despite the higher mass of the web of Example 9.

Hybrid blends of Blend 1 (eg 15%) and Blend 2 (eg 15%) can be used to produce similar sound absorption effects.

In Examples 11, 12 and 13, as shown and disclosed with respect to FIGS. 9, 10 and 11, two layers of sound absorbing materials, which are film surfaces, were combined one on top of the other. Sound absorption was measured using only a small 27 mm tube, according to ISO 1050. The material properties of the double layer sound absorbing material are provided in Table 2 below.

Example  11 Example  12 Example  13 Film description Linear Low Density Polyethylene Transparent Embossing Film 15μm (app 14.5gsm) Linear Low Density Polyethylene Transparent Embossing Film 15μm (app 14.5gsm) Linear Low Density Polyethylene Transparent Embossing Film 15μm (app 14.5gsm) Adhesive mechanism Adhesive fiber Adhesive fiber Adhesive Fiber & LDPE Adhesive Powder Nominal web density, g / m ² , layer 1 350 200 200 Nominal web density, g / m ² , layer 2 350 350 350 Nominal thickness, mm, layer 1 20 17 16 Nominal thickness, mm, layer 2 20 23 23 Nominal overall thickness, mm 40 40 39

As shown in FIG. 12, the results show a significant increase in lower frequency absorption without compromising high frequency sound absorption characteristics. This represents the increase in sound absorption obtained by forming a multilayered composite of self-laid sound absorbing material 200, as described herein and when assembled according to Examples 11, 12, and 13.

Acoustic weight efficiency is defined as the mass of a material divided by the noise reduction coefficient (NRC). NRC is the average of the sound absorption coefficients measured at each of the frequencies of 250, 500, 1000 and 2000 Hz. The acoustic weight coefficient of some disclosed embodiments and / or samples is considerably higher than commodities such as acoustic felt produced by The Simis family of Sydney, Australia. The inventors contemplate that the disclosed embodiments provide sound absorbing materials that have a lower weight and provide higher sound absorption performance. This feature can be important in the automotive sector because weight reduction can improve fuel economy of automobiles using sound absorbing materials.

Reference herein to any prior publication (or information obtained therefrom) or any known content is directed to the field of effort to which this prior publication (or information obtained therefrom) or any known content relates. It should not be construed as an admission or approval or any form of assertion that it constitutes part of general knowledge.

In this specification and in the following claims, unless otherwise stated, “comprises” and variations thereof do not exclude any other integer or step or group of integers or steps, but rather the aforementioned integer or step of integers or steps. Or it will be understood to mean including a group.

Embodiments have been described with reference to the drawings and embodiments. However, some modifications to the disclosed embodiments and / or examples can be made without departing from the spirit and scope of the disclosed embodiments, as disclosed in the appended claims.

Claims (46)

Forming a low density fibrous web that acts as a porous bulk absorber (the fibrous web comprises a plurality of bicomponent fibers, each bicomponent fiber having a sheath material around the core material and the core material, the sheath material Has a lower melting point than the core material);
Applying a surface layer to the fibrous web, where the surface layer is suitable for adhering to the sheath material;
Heating the fibrous web to a temperature sufficient to soften the sheath material of at least a portion of the bicomponent fiber;
Compressing the surface layer and the fibrous web together under low pressure to contact at least a portion of the surface layer with the softened sheath material of at least a portion of the bicomponent fiber to form an adhesive bond between the surface layer and the fibrous web. The method of claim 1,
And wherein the thin surface layer comprises a material selected from the group consisting of polymer films, foils and fibers. The method according to claim 1 or 2,
And the thin surface layer comprises a material selected from the group consisting of polyethylene, polyester, polyamide and polypropylene. The method according to any one of claims 1 to 3,
Low density fiber webs have an airflow resistance of at least about 1,000 mks Rayls / m and less than about 60,000 mks Rayls / m. The method according to any one of claims 1 to 4,
The low density fibrous web has a density of at least about 10 kg / m ³ and less than about 120 kg / m ³ . 6. The method according to any one of claims 1 to 5,
The thickness of the fibrous web after compression is reduced to about 5% to 80% of the thickness of the fibrous web before compression. The method according to any one of claims 1 to 6,
And wherein the fibrous web comprises heat bonded nonwoven fibers. The method according to any one of claims 1 to 7,
The fiber web includes a vertically wrapped fiber web. The method according to any one of claims 1 to 8,
The outer material of the bicomponent fiber is selected from the group consisting of polyethylene, polyamide, polypropylene and co-polyester. The method according to any one of claims 1 to 9,
The thin surface layer comprises a film layer having a thickness of about 5 to about 100 microns. The method of claim 10,
The film layer has a thickness of about 10 microns to about 25 microns. The method according to any one of claims 1 to 11,
The fibrous web has a thickness of about 4 mm to about 50 mm. The method according to any one of claims 1 to 12,
The surface layer is a first surface layer applied to the first side of the fibrous web and further comprising applying a second surface layer suitable for adhering to the sheath on the second surface of the fibrous web. The method of claim 13,
Compressing the second surface layer and the fibrous web together under low pressure such that at least a portion of the second surface layer contacts the softened sheath material of at least a portion of the bicomponent fiber to form an adhesive bond between the second surface layer and the fibrous web. Sound absorption material manufacturing method. The method according to claim 13 or 14,
The first and second surface layers each comprise a film layer of the same material. The method according to claim 13 or 14,
A method for producing a sound absorbing material, each of the first and second surface layers comprising a film layer of a different material. The method according to any one of claims 13 to 16,
The fibrous web is a first fibrous web and further comprises compressing the second low density fibrous web together under low pressure to weakly bond the first side of the second fibrous web to the second surface layer, wherein the second fibrous web A method for producing a sound absorbing material, each comprising a core material and a plurality of bicomponent fibers having a shell material around the core material, wherein the shell material has a lower melting point than the core material. The method of claim 17,
Before compressing the second fibrous web with the second surface layer, softening the sheath material of the bicomponent fibers in the second fibrous web such that an adhesive bond is formed between the second fibrous web and the second surface layer when compressed together under low pressure. Heating the first side of the second fibrous web. The method of claim 17,
Before compressing the second fibrous web with the second surface layer, further comprising applying an adhesive material to the first side of the second fibrous web suitable for bonding both the second surface layer and the first surface layer. . The method of claim 19,
Activating the adhesive material. The method of claim 20,
The activation step comprises thermal activation. 22. The method according to any one of claims 19 to 21,
And the adhesive material comprises a dry thermoplastic hot melt resin. The method according to any one of claims 17 to 22,
And applying a third surface layer suitable for adhering to the sheath material of the bicomponent fibers of the second fibrous web on the second side of the second fibrous web. The method of claim 23,
And heating the second fibrous web to a temperature sufficient to soften the sheath material of at least a portion of the bicomponent fibers. The method of claim 24,
Compressing the third surface layer and the second fibrous web together under low pressure such that at least a portion of the third surface layer contacts the softened sheath material of at least a portion of the bicomponent fiber to form an adhesive bond between the third surface layer and the second fibrous web. The sound absorbing material manufacturing method further comprising the step. The method according to any one of claims 1 to 25,
The linear mass density of the bicomponent fiber is from about 2 to about 6 denier. A sound absorbing material formed by the method of any one of claims 1 to 26. A low density fibrous web that acts as a porous bulk absorber (the fibrous web comprises a plurality of bicomponent fibers, each bicomponent fiber having a sheath material around the core material and the core material, the sheath material being less than the core material). Has a lower melting point); And
A sound absorbing material comprising a thin surface layer adhered to a fibrous web by an adhesive bond formed between the outer material and the surface layer of at least a portion of the bicomponent fiber. 29. The method of claim 28,
And the thin surface layer comprises a material selected from the group consisting of polymer films, foils and fibers. The method of claim 28 or 29,
And the thin surface layer comprises a material selected from the group consisting of polyethylene, polyester, polyamide and polypropylene. The method according to any one of claims 28 to 30,
Low density fiber webs are sound absorbing materials having an air flow resistance of at least about 1,000 mks Rayls / m and less than about 60,000 mks Rayls / m. The method according to any one of claims 28 to 31,
Low density fiber webs are sound absorbing materials having a density of at least about 10 kg / m ³ and less than about 120 kg / m ³ . The method according to any one of claims 28 to 32,
The fibrous web includes sound absorbing nonwoven fibers. The method according to any one of claims 28 to 33, wherein
The fiber web is a sound absorbing material comprising a vertically wrapped fiber web. The method according to any one of claims 28 to 34, wherein
The outer material of the bicomponent fiber is a sound absorbing material selected from the group consisting of polyethylene, polyamide, polypropylene and co-polyester. The method according to any one of claims 28 to 35,
The thin surface layer includes a film layer having a thickness of about 5 to about 100 microns. The method of claim 36,
The sound absorbing material, wherein the film layer has a thickness of about 10 microns to about 25 microns. The method according to any one of claims 28 to 37,
The fibrous web has a thickness of about 4 mm to about 50 mm. 39. The method of any of claims 28-38,
The thin surface layer is a first surface layer applied to the first side of the fibrous web and the sound absorbing material comprises a second thin surface layer adhered to the fibrous web by an adhesive bond formed between the outer material and the second thin surface layer of at least a portion of the bicomponent fiber. Sound absorbing material further comprising. The method of claim 39,
The first and second surface layers each comprise a film layer of the same material. The method of claim 39,
Sound absorbing material, each of the first and second surface layers comprising a film layer of a different material. The method according to any one of claims 39 to 41,
The fibrous web further comprises a second low viscosity fibrous web that is the first fibrous web and acts as a porous bulk absorber, the second fibrous web comprising a plurality of bicomponent fibers, each bicomponent fiber having a core Sound absorbing material having a shell material around the material and the core material, the shell material having a lower melting point than the core material, and wherein the second fibrous web is bonded onto the first side of the second fibrous web to the second surface layer. 43. The method of claim 42,
The second fibrous web is bonded to the second surface layer by an adhesive material suitable for bonding with the second surface layer. The method of claim 43,
The adhesive material includes a heat activated dry thermoplastic resin. The method of any one of claims 42-44,
The sound absorbing material further comprising a third surface layer adhered to the second fibrous web by an adhesive bond formed between the envelope material and the third surface layer of at least a portion of the bicomponent fibers of the second fibrous web. The method according to any one of claims 28 to 45,
Sound absorbing material wherein the linear mass density of the bicomponent fibers is from about 2 to about 6 denier.

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